hammond



W. H. HAMMOND.

Escapement for Chronometers.

No. 25,261. Patented Aug. 30, 1859.

UNITED STATES PATENT OFFICE.

YVM. H. HAMMOND, OF NIHV YORK, Y.

ESCAPEMENT FOR CHRONOMETERS.

Specification of Letters Patent No. 25,261, dated August 80, 1859.

To all whom it may concern:

Be it known that I, V. H. T'TAMMOND, of the city, county, and State ofNew York, have invented certain new and useful Im provements in theEscapements for Chronometers and \Vatches; and I do hereby declare thatthe following is a full, clear, and exact description thereof, referencebeing had to the accompanying drawings, making part of thisspecification, in which Figure 1, is a plan of the said movement; Fig.2, a sectional plan just below the balance; and Fig. 3 another sectionalplan just below the escapement wheel.

The same letters indicate like parts in all the figures which are on anenlarged scale.

My said invention relates to improvements in watches and chronometerswith the view to render the escapement more sure and to guard againstirregularity of movement. And the nature and scope of my said inventionwill be better comprehended after understanding the mode of constructionand operation.

In the accompanying drawings (a) represents the escapement wheel movedby any of the usual means employed in watches, the teeth of which insuccession give the required impulse to the balance wheel (5) by comingin contact with the pallet (c) on the cylinder ((3) of the verge orarbor of the balance wheel. This impulse turns the balance wheel in onedirection which winds up the hair spring (7) the tension of which thenturns the balance back the other way.

The moment one tooth of the escapement wheel has passed and given theimpulse to the balance it must be stopped until the pallet on the vergeis brought to the right posit-ion to receive another impulse from thenext tooth of the escapement wheel. This alternate holding and releasingof the escapement wheel is effected by a vibrating hollow semi-cylinder(g) attached to the arbor of a vibrating lever The hollow side of thevibrating semi-cylinder is to ward the escapement wheel. It should be ofa. diameter a little less than the distance between any two teeth of theescapement wheel so that when the vibrating lever is in the positionrepresented by full lines in the drawing one tooth of the escapementwheel bears against, and is held in repose by the outer surface of thesemi-cylinder, the overlapping being such that when the lever (2')vibrates to the opposite direction, and reaches the position representedby red lines in Fig. 3, the tooth of the wheel is liberated, and thewheel is turned by the motive power, that is, by the main spring, untilthe same tooth strikes against, and is arrested by the inner face of thehollow semi-cylinder on the opposite side of its axis of vibration, andthere the escapement wheel is held in repose until the lever with thehollow semi-cylinder, vibrates back to the first position represented byfull lines. which permits the tooth to escape fromthis inner face of thesemi-cylinder the next tooth being in turn stopped in the same manner,as before described, by coming in contact with the outer face of thesemicylinder. I prefer to make the diameter of the semi-cylinder alittle less than the space between any two of the teeth of theescapement wheel, say just enough to permit one tooth of the wheel toescape from the inner face of the semi-cylinder before the next tooth isstopped, or brought to the state of repose by the outer surface on theopposite side of the axis of vibration. From the relative position ofthe escapement wheel and the semi-cylinder it will be seen, that thevibrations of the semi-cylinder, while any one tooth of the escapementrests against it, will not move back the escapement wheel, so that thevibrations are not impeded by the necessity, which usually exists inescapements, of moving back the wheel against the force of the motivepower to effect the escapement.

hen any one tooth of the wheel escapes from the outer to the innersurface of the semi-cylinder, another tooth gives the impulse to thebalance by striking against a pallet on the verge; this turns thebalance in the direction of the arrow thereby coiling up the hairspring, which finally arrests and then impels it in the reversedirection. The reciprocating rotary movement of the balance thus givenvibrates the lever alternately in one, and then in the oppositedirection, to effect the escapements of the escapement wheel from thesemi-cylinder, and

cylinder on the vibrating lever, substantially as described, incombination With the escapeinent Wheel and the balance and verge, as setforth.

2. And I also claim in combination with i Vitnesses: the escapement,substantially such as de- M. H. BISHOP, scribed, or any equivalenttherefor, the em- ANDREW DE LACY.

ploynient of the holding spring, substantially as and for the purposespecified.

M. H. HAMMOND.

